Steam power system



May 2, 1961 p, PRQFOS 2,982,102

STEAM POWER SYSTEM Filed May 12, 1959 INVENTOR. Poul Profos ATTORNEYS Uni d S at The present invention. relatesfto condensing steam power systems including a forced circulation boiler for the production of superheated steam, and more particularly to such systems inwhich the steam, after expansion in aturbine and subsequent condensation, is returned to the boiler through a plurality 'ot' economizers or feed water preheaters which are heated in 'part with steam entO 2,982,102 t t Met $1 9.1.

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these branch conduits contains a rate of flow control device. 1 t 1 Further according to the invention there may be provided a third parallel channel at the output end of the twoparallel channels already .described, this third channel beingconnected through branch lines to points of various temperature in the channel heated with turbine tapped from appropriate stages in the turbine and in part with steam separated out at a plurality of water-steam separators,-the first of these separators having an input connected to the boiler between the vaporizing and superheating surfaces thereof and the others of which take as their inputeach the water separated out by, the previous drawn at the separator as the operating pressure of the boiler increases. To minimize these losses it has been heretofore proposed to transferl to the feed water the heat content of the working substance so withdrawn, and

it is of course also known to obtain heat for feed water preheaters from steam tapped from the turbine.

Heating of the feedwater preheaters from a combination of these two completely independent heat sources, the capacity of which varies with theload, poses great difficulties in control of the final feed water temperature, the desired value of which itself depends upon the load. In systems employing these two heat sources for feed water preheating, a satisfactory control of the final feed water temperature has hitherto been available only by use of complicated, costly and delicate control systems.

The. invention surmounts these difiiculties. In accordance with the invention, the feed water flow path between condenser and boiler is, over at least a portion of its length, divided into two or more parallel channels,

one of which includes; preheaters heated with turbine steam whereas the other includes preheaters connected to the saturated steam output terminals of the water separators. I

In a preferred embodiment of theinvention, eachof the \parallel channelsiricludes a fiow control valve, preferably disposed atthe feed water inlet end thereto.

at points of varioustemperature, into'the channel whose preheaters are heated with turbine steam, and each of steam and being additionally connected to the channel whose preheaters are heated with separator steam. Each of these last melitioned branch lines also contains arate of flow control devicell The relative amounts of feed water passing through the individual channels can also be readily adjusted by providing each one with a feed pump.

Maximum heat recovery from the working substance withdrawn from the boiler at the first waterseparator is achieved in a steam power plant according to .the

invention if the lowest pressure separator has its water outlet connected through a desalting device to the channel of preheaters heated with the saturated steam taken ,from the separators.

The invention will now be further described with reference to the accompanying drawings in which the single figure of drawing constitutesa schematic diagram of'a steam power system. according to the invention.

Inthe drawing, reference character 1 indicates a forcedcirculation boiler whose final superheater, indicated at 2, connects with a steam line 'or conduit 3 leading to a multistage turbine 4. The turbine is shown mechanically coupled to analternator 4. The condensate developed in thecondenser 5 is sent to the feed water line 7 by means of a condensate pump 6. Line 7 divides at a junction 8 into parallel channels 9 and 9'. The channel 9 contains feed water preheaters 10 to 15 which are heated with steam tapped, at lines 60 to 65, from the turbine. Channel 9 also includes a firing up drum 16.

In the channel 9' there is provided a series of pre- 1 heaters 18 to 21 which are heated with saturated stearn takenfrom a water separator expansion column 17.

This column is fed at an inlet 24 with that part of the working substance withdrawn from the boiler by a water separator 23 whichjis not returned by separator 23 directly to the boiler. Separator-23 is connected to the,

' boiler at a location in the tube system of the boiler bethe steam is returned to the boiler for superheatingand tween its vaporizing andsuperheating surfaces. The separator has an inlet at.66, a dry steam outlet at 67 at which delivery to the turbine, and a water outlet 68 which conects to the column inlet 24 through a valve 69. Water separators are well known devices, and the construction thereof 'need not be further described here. One form of separator, suitable for use as the separator 23 in the system of the drawing, is described in the article entitled The Action of the Water Separator in the Sulzer Monotube Steam Generator appearing at pages 14 to 21 of the Sulzer Technical Review, No. 1 of 1951. Separator Y 23 and column 17 together constitute plural-stage watersteam separating means connected to the boiler. Valve 69 may be operated, if desired, by means of a regulating device 70, shown coupled by dashed lines to the valve 69, and which device may be responsive to ternperature and/or pressure and/or water. level conditions in theseparator vessel. Suitable apparatus for use in such a regulating device is disclosed in my copending application Serial No. 798,418 filed March 10, 1959. Alternatively valve 69 may be manually controlled.

Inlet 24 is disposed tangentially of the column 17. Within the column 17 the working substance entering at inlet 24 is progressively reduced in pressure by throttling at the separating stages 25, 26, 27 and 28, being par-.

and a water outlet which connects. through a control valve 71, with a tangential input 24' to the next lower pressure stage of the column. The steam outlet of the highest pressure stage 25 connects to the preheater 21 at the high temperature end of channel 9', and the next lower pressure stage 26 similarly connects to the next lower temperature 'preheater 20 of channel 9', and so on. At the last separating stage 28 of column 17 the residual water, containing a high percentage of salts, passes through a cooler 29, through the desalting device 30 and thence through a throttling valve 31 and the conduit 32 into the feed water pump 33 of channel 9'.

3 Between the feed water input line 7 for feed water and the parallel channels 9 and 9'. there is provided a junction line 34 having three branches" 35, 36 and 37 connecting at points 38,3? and 40 in the channel 9. Branch line 35 contains 'a valve '41, and similar valves 42 and 43 are disposed in the branches 36 and 37.

The channel 9' is provided at its input end with a rate of flow control device 44, which may take the form of a valve. According as, by settingof valves 41, 42 and 43, the channel 9' is fed at junction 38, junction 39 or junction 40, the feed water enters channel 9 at a lower or higher temperature. Proportioning of the quantity of feed water passing through the channels 9 and 9 is effected by appropriate adjustment of the control device 44 and of one of the valves 41, 42 and 43. Alternatively if these valves 41, 42 and 43 are wide open, proportioning with respect to heat is achieved by adjustment of the pumps 33 and 45. Atthe water outlet end of channels 9 and ya third parallel-connected channel 51 is provided having branch lines 46 to 50, the channel 51 opening into channel 9 at the outlet end 52 thereof. Valves 53 to 57 are disposed respectively one in each of the branch lines 46 to 50, and these valves make it possible to bring the feed water emerging at 52 from the channel 9 together with the feed water in the channel 9 at a point where the two streams of feed water have thesame temperature. Control of the quantity of the feed water passing through channel 9 can be effected by operation of the valve 58. Of course the residual water separated out at the lowermost stage 28 in the column 17 can be discharged to the atmosphere at a valve 59, instead of being returned to the feed water-steam circuit through desalting device 30.

While the invention has been described herein in terms of a preferred embodiment, the invention itself is not restricted thereto, being rather set forth in the appended claims, and while the claims refer to water, it is to be understood that the invention may be embodied in power systems employing other materials as the working substance.

' Iclaim:

1. A steam'power plant comprising evaporating means and superheating means, a steam consuming machine, and two pluralities of preheaters all connected into a closed circuit, said preheaters being arranged in two parallelconnected groups to form two feed water channels, said channels being connected in parallel between'the low pressure end of said machine and said evaporating means, said plant further comprising means to withdraw steam from said machine at a plurality of pressure points, water-steam separating means connected to said firstnamed means, said separating means having a plurality of stages, means to apply toeaeh of the preheaters of one of said groups steam separated at one of said stages, and

means to apply to each of the preheaters of said other group steam withdrawn from said machine at one of said pressure points.

2. A steam power plant comprising evaporating means and superheating means, a steam consuming machine, and two pluralities' of preheaters all connected into a closed circuit, said preheaters being arranged in two parallelconnected groups to form two feedwater channels connected in parallel between the low pressure end of said machinean'd' said evaporating means, said plant further comprising means to withdraw steam from said machine at a plurality of pressure points, water-steam separating means connected to said first-named means, said separating means having a plurality of stages, means to apply to each of the preheaters of one of said groups steam separated at one of said stages, means to apply to each of the preheaters of the other of said groups steam withdrawn from said machine at one of said pressure points, and separate means to control the flow of feed water through each of said channels.

3. A steam power plant comprising evaporating means and superheating means, a steam consuming machine, and two pluralities of preheaters all connected into a closed circuit, said preheaters being arranged in two parallel-connected groups to form two feed water channels connected both at one end to said evaporating means, said plant further comprising means to withdraw steam from said machine at a plurality of pressure points, steam-water separating means connected to said evaporating means, said separating means having a plurality of stages, means to apply to each of the preheaters of one of said groups steam separated at one of said stages, means to apply to each of the preheaters of the other of said groups steam withdrawn from said machine at one of said pressure points, and conduit means connected between the low pressure-end of said machine and said channels, 'said conduit means including a plurality of branches connecting each into one of said channels between two adjacent of the preheaters therein.

4. A steam power plant comprising evaporating means and superheating means, a steam consuming machine, and two pluralities of preheaters all connected into a closed circuit, said preheaters being arranged in two parallelconnected groups to form two feed water channels connected both at one end to said evaporating means, said plant further comprising means to withdraw steam from said machine at a plurality of pressure points, steamwuter separating means connected to said evaporating means, said separating means having a plurality of stages, means to apply steam separated at each of said stages to a separate one of the preheaters in one of said channels, means to apply steam withdrawn from said machine at each of said pressure points to a separate one of the preheaters in the other of said channels, conduit means connected between the low pressure end of said machine and said channels, said conduit means including a plurality of branches connecting each into said other one of said channels between two adjacent of the preheaters therein, and flow control means in each of said branches.

5. A condensing steam power system comprising evaporating means and superheating means, a plural-stage steam consuming machine, a condenser, two groups of preheaters, separate means connecting the preheaters of each of said groups in series to form two feed water channels, and conduit means connecting said channels in parallel between said condenser and the low temperature end of said evaporating means to form a closed circuit for the flow of a working substance through the system, said system further comprising plural-stage water-steam separatin' means connected to said evaporating means, means to apply steam separated at each of the stages of said separating means to a separate one of the preheaters of one of said channels, means to withdraw steam from said machine at a plurality of pressure points, means to apply steam withdrawn from said machine at each of said pressure points to a separate one of the preheaters in the other of said channels, said conduit means including a plurality of branches connecting each into the other of said channels between a pair of adjacent preheaters therein, and rate of flow control means in each of said branches.

6. A condensing steam power system comprising evaporating means and superheating means adapted to generate superheated steam, a steam consuming machine, a condenser, two groups of preheaters, separate means connecting the preheaters of each group in series to form two feed water channels, water-steam separating means connected to said evaporating means, said separating means having a plurality of stages, means to withdraw steam from said machine at a plurality of pressure points,

means to apply steam from each of said stages to a separate one of the preheaters in one of said channels, means to apply steam from each of said pressure points to a separate one of the preheaters in the other of said channels, means connecting the feed water outlet of said condenser to each of said channels, means connecting the low pressure end of said evaporating means to the end of each of said channels remote from said condenser, a third channel arranged at said remote ends of said channels, said third channel having a plurality of branches each connecting into the other of said two feed water channels between adjacent preheaters therein, and flow control means in each of said branches.

7. A condensing steam power system comprising evaporating means and superheating means adapted to generate superheated steam, a steam consuming machine, a condenser, two groups of preheaters, separate means connecting the preheaters of each group in series to form two feed Water channels, water-steam separating means connected to said evaporating means, said separating means having a plurality of stages, means to withdraw steam from said machine at a plurality of pressure points, means to apply steam from each of said stages to a separate one of the preheaters home of said channels, means to apply steam from each of said pressure points to a separate one of the preheaters in the other of said channels, means connecting the feed water outlet of said rating means andsuperheating means adapted to generate superheated steam, a steam consuming machine, two groups of preheaters, separate means connecting the preheaters of each group in series to form two feed water channels, water-steam separating means connected to said evaporating means, said separating means having a plurality of stages, means to withdraw steam from said machine at .a plurality of pressure points, means to apply steam from each of said stages to a separate one of the preheaters in one of said channels, means to apply steam from each of said pressure points to a separate one of the preheaters in the other of said channels, means connecting said channels in parallel between the low pressure end of said machine and the low temperature end of said evaporating means, and a feed water pump in each of said channels. V

9. A condensing steam power system comprising evaporating means and superheating means adapted to generate superheated steam, a plural-stage steam consuming machine, two groups of preheaters, separate means connecting the preheaters of each of said groups in series to form two feed water channels, means connecting said channels in parallel between the low pressure end of said machine and the low temperature end of said evaporating means, said system further comprising a desalting means, plural-stage water-steam separating means connected at one end to said evaporating means and at the other end, through said desalting means, to one of said channels, means to apply to each of the preheaters in said one of said channels steam separated at one of said stages, means to tap steam from said machine at a plurality of pressure points, and means to apply to each of the preheaters in the other of said channels steam from one of said pressure points.

References Cited in the tile of this patent UNITED STATES PATENTS 1,838,007 Smith Dec. 22, 1931 1,852,640 Baumann Apr. 5, 1932 FOREIGN PATENTS- 1,021,451 France Feb. 19, 1953 

